The invention concerns a control system for roads and motorways adapted to signal timely to arriving motor vehicles the presence of any obstructions along the roads, which system therefore is particularly suitable in the case of accidents in fog or inside tunnels, traffic jams etc.
Those who travel by motor-vehicle know that a sudden accident or heavy traffic represents a sudden barrier in front of the motor-car in which they are travelling, thereby resulting in a sudden reduction of the available useful braking distance. Therefore it is relevant that the obstruction be timely signalled in advance. This factor is more true the more critical is the traffic, such as in the presence of fog, rain, tunnels, viaducts etc. There are known systems adapted to signal the presence of traffic jams along motorways such as lighting panels or signalling devices provided on the motorway or panels with sliding information on police cars. Still important, such means cannot be available immediately and, when they are available, the number of cars involved in the accident has already increased.
Therefore, it is an object of the invention to provide a fully autonomous means for signalling the presence of an obstruction in as short a time as possible so as to limit the possible damage to cars already involved in the accident.
The above object is accomplished by providing a traffic control system for timely signalling the presence of an obstruction on a roadway which includes a plurality of vehicle detecting units spaced along the roadway. Each vehicle detecting unit includes a control plant having means for sensing motor vehicles on the roadway, timer means for receiving signals from the sensing means indicating the presence of motor vehicles and filtering the signals to pass only signals longer than a pre-established time, a central control unit interfaced with the timer means to receive the signals passed by the timer, alarm means actuated by the central control unit upon receipt thereby of a signal from the timer means, radio transmitter units which transmit a signal to adjacent detecting units to activate the alarm means of the adjacent detecting units upon activation by the central control unit upon receipt by the central control unit of a signal from the timer means, radio receiver units for receiving signals from adjacent detecting units so as to activate the alarm means, and an electric power source for powering the control plant.